At present a User Equipment (UE) is configured with only one carrier resource of no more than 20M in a Long Term Evolution (LTE) system, and since there is only one carrier in the system, a handover procedure is performed directly over the carrier when the user equipment in the system is handed over from an eNB originally serving the user equipment (i.e., a source eNB) to another eNB (i.e., a destination eNB).
Carrier aggregation supported in LTE-Advanced includes aggregation of consecutive carriers as well as in-band and inter-band aggregation of inconsecutive carriers and has a maximum bandwidth that can be aggregated of up to 100 MHz. Thus 1 to 5 component carriers can be supported in a macro cell, and each component carrier shall be able to be configured as a carrier backward compatible with LTE in order to make LTE-A compatible with LTE, so each component carrier has a bandwidth of no more than 20M. In the foregoing application scenario of carrier aggregation, a component carrier has to be selected in the handover procedure while the user equipment is being handed over from the source eNB to the destination eNB. Unfortunately a technical solution of supporting the handover of the user equipment from the source eNB to the destination eNB in the carrier aggregation scenario has been absent in the existing LTE-A system.